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Will giant polar amphipods be first to fare badly in an oxygen-poor ocean? Testing hypotheses linking oxygen to body size

Abstract.

"It has been suggested that giant Antarctic marine invertebrates will be particularly vulnerable to declining O2 levels as our ocean warms in line with current climate change predictions. Our study provides some support for this oxygen limitation hypothesis, with larger body sizes being generally more sensitive to O2 reductions than smaller body sizes. [...]"

Source: Philosophical Transactions of the Royal Society B
Authors: John I. Spicer  and Simon A. Morley
DOI: 10.1098/rstb.2019.0034

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The complex fate of Antarctic species in the face of a changing climate

"Researchers have presented support for the theory that marine invertebrates with larger body size are generally more sensitive to reductions in oxygen than smaller animals, and so will be more sensitive to future global climate change. However, evolutionary innovation can to some extent offset any respiratory disadvantages of large body size. [...]"

Source: Science Daily / University of Plymouth

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Nitrifier abundance and diversity peak at deep redox transition zones

Abstract.

"More than half of the global ocean floor is draped by nutrient-starved sediments characterized by deep oxygen penetration and a prevalence of oxidized nitrogen. Despite low energy availability, this habitat hosts a vast microbial population, and geochemical characteristics suggest that nitrogen compounds are an energy source critical to sustaining this biomass. [...]"

Source: Scientific Reports
Authors: Rui Zhao et al.
DOI: 10.1038/s41598-019-44585-6

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Fish debris in sediments from the last 25 kyr in the Humboldt Current reveal the role of productivity and oxygen on small pelagic fishes

Abstract.

"Upwelling of cold, nutrient-rich water from the oxygen minimum zone (OMZ) off Peru sustains the world’s highest production of forage fish, mostly composed of anchovy (Engraulis ringens). However, the potential impacts of climate change on upwelling dynamics and thus fish productivity in the near future are uncertain. Here, we reconstruct past changes in fish populations during the last 25,000 years to unravel their response to changes in OMZ intensity and productivity. [...]"

Source: Progress in Oceanography
Authors: RenatoSalvatteci et al.
DOI: 10.1016/j.pocean.2019.05.006

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Antarctic offshore polynyas linked to Southern Hemisphere climate anomalies

Abstract.

"Offshore Antarctic polynyas—large openings in the winter sea ice cover—are thought to be maintained by a rapid ventilation of deep-ocean heat through convective mixing. These rare phenomena may alter abyssal properties and circulation, yet their formation mechanisms are not well understood. Here we demonstrate that concurrent upper-ocean preconditioning and meteorological perturbations are responsible for the appearance of polynyas in the Weddell Sea region of the Southern Ocean. [...]"

Source: Nature
Authors: Ethan C. Campbell et al.
DOI: 10.1038/s41586-019-1294-0

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Massive 8,000-mile 'dead zone' could be one of the gulf's largest

"JUST OFF THE coast of Louisiana and Texas where the Mississippi River empties, the ocean is dying. The cyclical event known as the dead zone occurs every year, but scientists predict that this year's could be one of the largest in recorded history. Annual spring rains wash the nutrients used in fertilizers and sewage into the Mississippi. That fresh water, less dense than ocean water, sits on top of the ocean, preventing oxygen from mixing through the water column. Eventually those freshwater nutrients can spur a burst of algal growth, which consumes oxygen as the plants decompose. [...]"

Source: National Geographic

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NOAA forecasts very large ‘dead zone’ for Gulf of Mexico

"NOAA scientists are forecasting this summer’s Gulf of Mexico hypoxic zone or ‘dead zone’ – an area of low to no oxygen that can kill fish and other marine life – to be approximately 7,829 square miles, or roughly the size of Massachusetts. The annual prediction is based on U.S. Geological Survey river flow and nutrient data. [...]"

Source: NOAA

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World Oceans Day: Scientists ‘taken aback by scale and speed of ocean changes’

"Armed with better data than ever before, scientists have in recent months sounded the alarm over the rising pace of global warming and the parlous state of Nature. But there is another area of concern, one that covers two thirds of the planet and plays a crucial role in absorbing dangerous greenhouse gases and regulating everything from food chains to weather patterns. Oceans are crucial to life on Earth, yet they frequently only feature in the environment debate when plastic pollution or fish-stock declines are discussed. But experts believe that might be changing. “We have an important opportunity over the next 18 months to do something for oceans,” said Dan Laffoley, from the International Union for the Conservation of Nature. [...]"

Source: France24

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Gas exchange estimates in the Peruvian upwelling regime biased by multi-day near-surface stratification

Abstract.

"The coastal upwelling regime off Peru in December 2012 showed considerable vertical concentration gradients of dissolved nitrous oxide (N2O) across the top few meters of the ocean. The gradients were predominantly downward, i.e., concentrations decreased toward the surface. Ignoring these gradients causes a systematic error in regionally integrated gas exchange estimates, when using observed concentrations at several meters below the surface as input for bulk flux parameterizations – as is routinely practiced. [...]"

Source: Biogeosciences
Authors: Tim Fischer et al.
DOI: 10.5194/bg-16-2307-2019

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Effects of ocean acidification on the respiration and feeding of juvenile red and blue king crabs (Paralithodes camtschaticus and P. platypus)

Abstract.

"Ocean acidification is a decrease in pH resulting from dissolution of anthropogenic CO2 in the oceans that has physiological effects on many marine organisms. Juvenile red and blue king crabs (Paralithodes camtschaticus and P. platypus) exhibit both increased mortality and decreased growth in acidified waters. In this study, we determined how ocean acidification affects oxygen consumption, feeding rates, and growth in both species. [...]"

Source: ICES Journal of Marine Science
Authors: William Christopher Long et al.
DOI: 10.1093/icesjms/fsz090

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